The salient findings among the recently completed studies are: (l) Using crop-sac weight as end point, treatment with CB-154 did not produce any suppressive effect in doves, a finding contrary to the finding in mammals. (2) Direct estrogen implantation in the region of n. intercolliculari an estrogen sensitive site, induced nest-coo behavior in the ovariectomized female ring doves. This is a relatively specific effect in comparison with other estrogen-sensitive sites such as posterior medial hypothalamus where central estrogen stimulation reinstates both sexual crouch and nest-coo behavior, with the latter at low rate. (3) Ring doves appear to copulate more than necessary to fertilize eggs; these excess copulations occurring before the pre-ovulatory hormonal stage did not result in fertilizing eggs.